The present invention relates to an emergency support member for a vehicle wheel and tire assembly having a pneumatic tire that is mounted on a wheel rim and essentially has a tread strip, two sidewalls, a carcass, reinforcing elements, as well as two tire beads that are provided with bead cores, whereby the emergency support member is embodied as a dished annular member within the tire and has an emergency support surface for supporting the tire in the event of damage thereto, whereby the dished annular member extends axially from the center of the rim symmetrically over a portion of the width of the rim, and when viewed in cross-section, axially outer portions of the annular member have a contour that is provided with first curvatures that are open toward the rim, and a central portion of its cross-section, between the curvatures that are open toward the rim, has a contour that is provided with a second curvature that is open toward the base of the tread strip, whereby the curvatures have one or more radii of curvature that uniformly merge with one another, and whereby the two axially outer wall portions of the dished annular member are supported upon the wheel rim via ring-shaped or annular support elements.
A one-piece emergency support member, i.e. a rim that is provided with such an emergency support member, is disclosed in DE-OS 35 07 046, whereby this known emergency support member is comprised of an outer metallic reinforcing ring, and a cushioning ring that is disposed between the reinforcing ring and the rim.
With such a one-piece configuration, the diameter of the metallic reinforcing ring is limited by the requirements for mounting an assembly. Although the outer diameter of such a one-piece ring should be as large as possible in order to achieve good emergency running characteristics, nonetheless this requirement is in conflict with the mounting conditions, according to which the metallic reinforcing ring must be introduced into the tire through the diameter of the cores. This core diameter refers to the diameter of the tire beads that contain the cores, and which correspond essentially to the diameter of the rim.
In addition, the manufacture of such a one-piece metallic reinforcing ring is relatively complicated and is generally effected by roll turning or cylindrical rolling (roll forming) of an annular blank, or by the annular welding of a coiled stock, whereby in each case this is a time and manufacturing intensive piece production.
It is therefore an object of the present invention to provide an emergency support member that, even with an optimized configuration over its cross-section, can be produced easily and reliably, is easy to mount or assemble in its final form, and permits a trouble-free connection with necessary support elements without cushioning rings, and that can be manufactured with the diameters, and can be mounted into the tires in a manner, that are optimum for an emergency rolling contact and not limited by the core diameter of the tire.
The inventive emergency support member, and a vehicle wheel and tire assembly having such an emergency support member, are characterized primarily in that the dished annular member is embodied as a split ring that is not closed over its periphery but rather is provided with a slit formed between two oppositely disposed ends of the dished annular member, and by a means or closure for closing off the slit, wherein such closure includes two flanges that are disposed on the oppositely disposed ends of the dished annular member that form the slit, wherein such flanges extend essentially radially inwardly relative to the wheel rim, and wherein the closure further includes at least one locking clamp for connecting the flanges.
As indicated, the dished annular member is first of all embodied as a ring, designated a split ring, that is not closed over its periphery. With such a configuration, an annular member that is provided with an optimized contour, and with an as large as possible diameter that is optimized for the rolling contact behavior in an emergency operating condition, can be introduced and mounted into the tire without difficulty. Due to the fact that the annular member is provided with a slit, it is possible to introduce the not yet closed off annular body into the tire via a helical mounting movement without being obstructed by the diameter of the core. The closing off of the annular member is effected only after introduction of the annular member into the tire.
By means of such a configuration, the annular member can advantageously also be produced in the form of a continuous screw from coiled stock in a continuous rolling process, for example by means of a 3-roller bending machine that is provided with appropriate complementarily embodied rollers. This endless screw is then cut in conformity with the required rim and tire circumferences, as a result of which individual slitted rings having the required diameter and the desired cross-sectional contour are produced.
The dished annular member is then provided with a device or closure for closing off the slit, with this device including two flanges that are disposed on the respectively oppositely disposed ends of the dished annular member that form the slit, with the flanges extending essentially radially inwardly relative to the wheel rim.
The flanges advantageously have base elements or regions that are adapted to the contour of the annular member and via which the flanges are connected with the annular member, for example by a multiple spot welding or by a seam weld. The flanges could also be provided with support plates that additionally protect the locking clamp from bending out or up under load.
The dished annular member is furthermore provided with at least one locking clamp that connects the flanges. The locking clamp is advantageously embodied as an essentially U-shaped clamp, the legs of which, in the installed state, extend radially outwardly relative to the wheel rim, and extend about those side surfaces of the flanges that are remote from the slit. As a consequence of such a configuration, even in the region of the slit or connection, the dished annular member has a stability that is readily suitable to absorb the high stresses or loads that occur during an emergency running operation.
Pursuant to one advantageous embodiment of the present invention, the closure means is provided with securing and/or connecting means between the flanges and the locking clamp that are preferably embodied as bolts that connect the flanges and clamp. Such bolts can have various configurations and can be secured in various ways, for example by being welded with the clamp and/or the flanges, or by being securely seated by means of spring or snap rings. Also advantageous for securing the bolt are spring clips or clamping springs that engage in an appropriate circumferential groove of the bolts. By using such spring clips or clamping springs, the emergency support member is easy to install and again remove.
Pursuant to a further and particularly advantageous specific embodiment, the dished annular member (split ring), which is embodied as a ring that is not closed over its periphery, has a slit that forms an angle of up to 50xc2x0 relative to the axis of the dished annular member, and hence also to the axis of the rim. With such a configuration, the high transverse forces in the region of the edges of the split that act upon the annular member, for example when driving through curves in an emergency running operation, are reliably transferred or dissipated without producing excessive stress peaks for the individual components. In particular, such an angular arrangement of the slit significantly reduces a difference in rigidity in the construction of the emergency support member under the stress of emergency or flat tire operation.
Further specific features of the present invention will be described in detail subsequently.